Three chemical agents have been shown to exert immuno-adjuvant activity to chemotherapy of established murine leukemias. In vitro studies demonstrate that these agents stimulate macrophages to exert a tumoricidal effect. T-cell lymphocytes are also stimulated by these agents. Two of these chemical agents are effective adjuvants for tumor cell vaccines. Pyran copolymer adjuvant acts with tumor cell free extracts to augment host immune response. Metastatic lesions in the lung are retarded as a result of surgery and immuno-adjuvant therapy.